Rust inhibitor for gasoline



2,919,979 RUST INHIBITOR FOR GASOLINE Eugene C. Martin, Texas City,Tex., and Harvey R. Titsworth, Baltimore, Md., assignors to The AmericanOil Company, Texas City, Tex., a corporation of Texas No Drawing.Application June 11, 1957 Serial No. 664,922

"5 Claims. (CI. 44-63) This invention relates to gasolines which containimproved rust inhibiting compositions.

v The rusting problem presented in connection with gasoline occursduring the storage and/or transportation thereof. Rusting may occur instorage tanks, pipelines, tanker vessels, automobiles, etc. Any rustinhibitor which is added to the gasoline must not cause the formation ofemulsions with water, which water is present in the storage tank,pipeline, tanker compartment, etc. and which causes the rusting tooccur. The rust inhibitor must not be precipitatedfrom the gasoline bythe high pressureswhich occur in pipeline transportation. Also, thecolor of the gasoline must not be changed by the addition of the rustinhibitor, i.e. the rust inhibitor must not cause a color change byreaction thereof with the hydrocarbons, antioxidants, dyes, componentsof tetraethyllead, sulfur, etc. which might be contained in thegasoline. This color problem is particularly troublesome when a non-dyedgasoline free of tetraethyllead is involved. In addition, the rustinhibitor must not adversely affect the octane rating of the gasoline,must not effect the operation of effectiveness of the other gasolineadditives, and must not cause the formation of excessive amounts of gumor sediment.

An object of this invention is to provide an improved rust inhibitor forgasoline. Another object is to provide a highly effective andinexpensive rust inhibiting composition for gasoline which does notadversely affect the other properties of the gasoline during storage,transportation, or use of the gasoline in combustion engines. Otherobjects and advantages of the invention will be apparent from thedetailed description thereof.

It has been found that these and other objects can be achieved byincorporating in a gasoline an amount between about 0.000] and 0.01percent by weight of a rust inhibiting composition which consists of anacylsarcosine and a 1,2-disubstituted imidazoline. composition may alsocontain tall oil. For example, an approximately equimolar mixture ofN-oleyl sarcosine and l-hydroxyethyl Z-heptadecenyl imidazoline may beemployed as the rust inhibiting composition. While each of theindividual components mentioned does have some I United States PatentThe rust inhibiting L rust inhibiting properties, the effectiveness ofthe mixture ofthe two components is more than additive, i.e. a

I synergistic and beneficial elfect is observed when the mix- RCONtCI-I)CH COOH in which R is an alkyl radical having from 8 to 20 carbonatoms. The alkyl radical may be a saturated or unsaturated groupinghaving either a straight or branched Patented Jan. 5, 1960 chain.Because the primarypurpose of the R grouping is to impart oil solubilityto the acylsarcosine molecule, its particular configuration and theexact number of carbon atoms contained in the R grouping are not ofcritical importance, provided it imparts oil solubility. Mixtures ofvarious acylsarcosine can be employed, or the individual acylsarcosinesmay be used. Those acylsarcosines whose alkyl radical is derived from anatural fatty acil composition are very satisfactory. For instancelauroyl-, stearoyl-, oleyl-, cocyl- (from cocoanut oil), sarcosines maybe used.

The acylsarcosines may be prepared by reacting the desired acylchloride(having from 8 to 20 carbon atoms) with the alkali metal salt of methylaminoacetic acid (frequently methyl glycine or sarcosine) to form thealkali metal acylsarcosinate which may then be partially hydrolized tothe desired acylsarcosine. The reactions which occur may be illustratedas follows:

The acylchlorides which may be used are those suitably derived fromnatural fatty acid compositions such as have been discussed previously.

The 1,2-disubstituted imidazoline which is used corresponds to thefollowing structural formula:

In the formula, R represents a hydrocarbon radical of 8 to 20 carbonatoms in length. It may be a saturated or unsaturated alkyl radical,having either a straight or branched chain. Since the primary functionof the hydrocarbon radical represented by R is to impart oil solubilityto the molecule, the particular number of carbon atoms contained thereinis not of critical importance. It is essential that the hydroxyethylgrouping be present in the disubstituted imidazoline.

The combined amount of the acylsarcosine and the disubstitutedimidazoline which is added to the gasoline may be between 0.0001 and0.01 percent by Weight. This corresponds to a range of 1 ppm. to ppm.Under severe rusting conditions such as occurs in seagoing tankers,amounts in the neighborhood of 0.001 to 0.003 per cent by weight (10 to30 ppm.) will be satisfactory. Under conditions less conducive torusting, amounts in the range of about 0.0005 to 0.001 percent by Weightcan be used satisfactorily. The amount of 0.001 percent by Weight isapproximately 2 /2lbs./ 1000 barrels of gasoline. While equimolarmixtures of the acylsarcosine and the disubstituted imidazoline are verysatisfactory, a wide range of ratios of these two components may beemployed. Thus, a molar ratio of from 0.1 to 10 mols of acylsarcosineper mol of disubstituted imidazoline may be contained in the rustinhibiting composition.

Tall oil, which has some rust inhibition properties of its own, can beemployed in the rust inhibiting composition added to the gasoline. Whenit is employed together with the mixture of acylsarcosine anddisubstituted imidazoline, it displays a synergistic and beneficialeffect. It is attractive to use due to its low cost. employed in theamount of about 1 to 10 mols per total number of mols of acylsarcosineand disubstituted imidazoline contained in the rust inhibitingcomposition.

Tall oil, which consists of a mixture of saturated and.

It may be 'tained by acidifying the black liquor skimmings obtained-frompulp wood in the sulfate (kraft) process.- The manufacture,purification,composition, etc. of tall oil is described in theEncyclopedia of Chemical Technology,

--volume 13, pages 572-7 (1954). Either crude tall oil or purified talloil may be used. Typical whole tail oils -have a color (Gardner) of9-12, an acid number of about 155-185, a saponification number of about158- 185, an iodine number of about 140-210, fatty acids content ofbetween about and percent, rosin acid content of 30 to percent and anuusaponified content of between 4 and 12 percent. Fractions of wholetall oils such as contain 70 to percent fatty acids, 1 to 4 percentrosin acid, and 2 to 5 percent of unsaponified materials are alsosatisfactory for use.

The acylsarcosine and disubstituted imidazoline (and inhibitingcomposition. This concentrate may be heated, e.g. to a temperature0f'100-175" F. (temperatures higher than 200 F. are believed to cause areaction which reduces the efiectiveness of the rust inhibitingcomposition) The effectiveness of the acylsarcosine, the disubstitutedimidazoline and the tall oil when each was employed individually as arust inhibiting composition was determined. Tests were also carried outwhich show that a mixture of the acylsarcosine with the disubstitutedimidazoline and a mixture of the acylsarcosine plus disubstitutedimidazoline plus tall oil provided unexpectedly greater effectivenessthan the effectiveness of the inditvidual components would havepredicted. The test procedure consisted of a standard ASTM D-665-54Trust test which as modified by employing synthetic seawater (to make thetest much more severe) in place of distilled water, and carrying out thetest at 80 F. rather than F. because of the volatility of the gasoline.Basically, the test is carried out by stirring a mixture of gasoline andthe synthetic seawater at 80 F. with cylindrical polished steelspecimens at a stirring-rate of about 1,000 rpm. for 20 hours. In orderfor a specimen to pass the test, it must not show a single rust spot orstreak when subjected to 60-foot candles illumination. The effectivenessof the rust inhibitor is determined by repeating the tests with varyingamounts of the inhibitor until the minimum amount of inhibitor necessaryto pass the rust test is determined. A comparison of the minimum amountsof the different rust inhibitors necessary to pass the test shows therelative effectiveness of the different rust inhibitors.

The rust inhibitors were tested in a gasoline which con- I tained no dyeor tetraethyllead fluid. Oleyl sarcosine (sold under the trade nameSarkosyl-O), l-hydroxyethyl Z-heptadecenyl imidazoline (sold under thetrade name I Amine-O), and tall oil (sold under the trade name AcintolFA-l) were individually tested in the modified ASTM rust test todetermine the minimum amount of each component necessary to pass therust test when the component was employed individually. The tall oil wasa fraction of whole tall oil having. the composition 92.5

. percent fatty acids, 3.5 percent rosin acids, and 4 percentunsaponified material. An-equimolar mixture of oleyl sarcosine andl-hydroxyethyl Z-heptadecenyl imidazoline .was heated to about F. forone hour and the mixture was then tested to determine itsrust-inhibiting eflfectiveness. To a portion of this heated equirnolarmixture This resultant three component mixturewas then tested it? th amne s r ahi i n ef ec ive s i mum quantity (expressed as weight percentbased upon gasoline) of the different rust inhibitors necessary in orderto pass the rust test is shown in the table which follows:

Table 1 Concentration RunNo. (Wt. Percent) Required to Pass Test 1 Oleylsarcosine-l-disubstituted imidazoline 0.003 2 Oleylsarcosiue-j-disubstituted 'unidazo- 0.0055

15 3 Oleylsareosine 0.0055 4 Disubstituted imidazoline 0.5 5- Tall nil01 1 l-hydroxyethyl Z-heptadeceuyl imidazoline.

Of the individual componrnts tested in runs 3, 4, and 5, oleyl sarcosineis by far the most effective. Only 0.0055 percent is necessary to passthe rust test.. More than 0.1 weight percent of tall oil and more than0.5 weight percent of the. disubstituted imidazoline are needed to passthe test when they are employed individually. Theoretically then, if thedisubstituted imidazoline is added in an equal amount to the oleylsarcosine, it would be expected that the total amount necessary to passthe test would lie half way between 0.0055 and 0.5 weight percent, i.e.about 0.25 weight percent. should befnecessary. Surprisingly, only 0.003weight percent is needed to pass the test. This clearly demonstrates thesynergistic effect obtained by using a mixture of the acylsarco'siue andthe disubstituted imidazoline. Similarly, if tall oil is added to amixture of oleylsarcosine and thefdisubstituted imidazoline, theexpected additivetype of effect would indicate that approximately 0.09weightpercent of this combination would be necessary in order to passthe test; whereas run No. 2shows th31oniy 0,0055 weight percent isneeded.

While the invention has been described with reference to certainspecific examples, the invention is-not to. be considered as limitedthereto but includes within its sc'ope such modifications and variationsas would occur to, one skilled in the art.

Thus having described the invention, what is claimed is: 1. A gasolinecontaining between. about 0.000l percent and 0.01 percent by weight of arust inhibitin'gcomposition consisting of an acylsarcosine correspondingto the formula RCON(CH )CH COOH and'a 1,,2 -,disub- 1 stitutedimidazoline corresponding to. the formula wherein R and R an: alkylradicalshaving 8 to 20 carbon atoms, wherein the molar ratio of theacylsarcosine to the-1,2-disubstituted imidazoline is between 01:1 and10:1, and said rust inhibiting comppsition having been subjected toheating to a temperature between about 100 to 200 F. V

2. The composition of claim 1 in which the rust inhibiting cornpositioncontains tall oil in anamounlt between about 1 to 10 mols per mol ofN-oleyl sarcosine.

3. A concentrate for addition to gasoline to produce a rust inhibitedgasoline, which.con,centrate consists essentialiy of a gasolinecontainingbetween-about 1 and 50 percent by weight of a rustinhibitingcomposition formula RCON(CH )CH COOH and a 1,2disubstituted imidazolinecorresponding to the formula /NCH2 R-C/ 11,011 wherein R and R' arealkyl radicals having from 8 to 20 carbon atoms, wherein the molar ratioof the acylsarcosine to the 1,2-disubstituted imidazoline is between0.1:1 and 10: 1, and said rust inhibiting composition having beensubjected to heating to a temperature between about 100 to 200 F.

4. A gasoline containing between about 0.0001% and 0.01% by weight of arust inhibiting composition consisting of N-oleyl sarcosine andl-hydroxyethyl Z-heptadecenyl imidazoline, the molar ratio of thesarcosine compound to the imidazoiine compound being from 0.1:1 to 10:1,and said rust inhibiting composition having been subjected to heating toa temperature between about 100 to 200 F.

5. The composition of claim 4 in which the rust inhibiting compositioncontains tall oil in an amount between about 1 to 10 mols per'mol ofsaid N-oleyl sarcosine.

References Cited in the file of this patent UNITED STATES PATENTS2,568,876 White et al Nov. 14, 1949 2,658,823 Andress Nov. 10, 19532,773,879 Sterlin Dec. 11, 1956 2,790,779 Spivak et a1. Apr. 30, 1957

1. A GASOLINE CONTAINING BETWEEN ABOUT 0.0001 PERCENT AND 0.01 PERCENTBY WEIGHT OF A RUST INHIBITING COMPOSITION CONSISTING OF ANACYLSARCOSINE CORRESPONDING TO THE FORMULA RCON(CH3)CH2COOH AND A1,2-DISUBSTITUTED IMIDAZOLINE CORRESPONDING TO THE FORMULA